Solar System Debris
Can You Answer the Following
COMETS IN GENERAL
1. Comets have played an important role in the history and evolution
of astronomical thought.
To the Greeks, they were "hairy stars,"
a phenomenon occurring in the earth's
_______________. Tycho Brahe (1546-1601) showed
that comets belonged to the realm
of the _________________. Isaac Newton (1643-1727)
__________________ based upon the universal
law of gravitation, while Edmund Halley
(1656-1742) proved that comets could make repeated
returns to the ________________.
2. A comet has been called the closest thing to nothing that anything
can be and still be
considered something. Although not a good definition
for a comet, it is a true statement.
3. Comets may represent the best example of the original, undifferentiated
material left over from
the formation of the solar system. In those
early days these bodies may have been catapulted
into the outer fringes of the solar system from
the gravitational effects of the planets
_______________ and _______________ working
in concert with U and N
latter planets drove the cometary bodies inward
towards the sun.
4. Supposedly, in the outer reaches of our solar system there is a
large region of billions and
billions of comets known as the _______________
5. _______________ moving near this cloud can cause some of these
comets to fall in towards
the _______________ where the major planets
eventually expel or modify their long period
orbits into orbits of shorter duration.
6. New comets entering the solar system for the first time have random
inclinations to the plane of
the ecliptic indicating that the shape of the
Oort cloud is _______________.
7. Comets which have orbital periods greater than 200 years are termed
period comets, while comets with orbital periods
of 200 years or less are called
_______________ period comets.
8. As a class of objects in the solar system, comets with periods
of 200 years or less are unique in
that their orbital eccentricities and inclinations
are, on average, much larger than the
_______________. However, almost all of these
comets revolve around the sun in the same
_______________ as the planets, indicating the
profound influence which the planets have had
on these objects. Halley's Comet is one of two
exceptions to this rule.
9. Comets with orbital motions which were originally clockwise were
from the solar system by the Jovian planets
or were gravitationally perturbed to orbit the sun in a
MORPHOLOGY OF A COMET
10. A comet approaching the sun can be likened to a dirty _______________.
It is mainly
composed of water _______________ mixed with
_______________. Other constituents
include frozen m______________, a_______________,
and c_________ d_________. .
11. The smallest part of the comet, described in the preceding question
as the dirty snowball, is
called the _______________. A typical diameter
may be _______________ miles. Comet
Hyakutake, which appeared in the spring of 1996
had a nucleus less than two miles (1-3 km) in
diameter. Hale-Bopp, which will be even more
prominent during the spring of 1997 has a
nucleus as great as 25 miles (40 km) in diameter
12. As sunlight heats the comet, the ices _______________, (change
directly into a gas). Pockets of gas form underneath
the comet's surface due to solar warming. When these areas "pop,"
escaping gasses drag the dust and other gritty
substances away from the nucleus to form the
_______________, the veiled region surrounding
the solid center.
13. This region around the nucleus, which may be hundreds of thousands
of miles in diameter, is
composed of neutral gases, some p_______________
and d_______________. Collectively,
the coma and nucleus of a comet are called the
14. Surrounding the coma and even part of the tail is a larger invisible
cloud or halo of excited
_______________ gas which can be millions of
miles in extent. This cloud also suggests that
one of the primary constituents of a comet's
nucleus is a very common compound called
_______________. This was confirmed by the Halley
flybys of 1986.
15. As a comet approaches the sun _______________ (type of energy)
radiation excites the
gases in the coma until they begin to glow or
f_______________. In this process, energy of a
shorter wavelength, which is invisible to the
human eye, is absorbed by the gases of the comet
and emitted as longer wavelengths, which can
be seen. Comets generate their own light.
16. The mechanism which creates one of the two types of tails a comet
may possess involves the
solar wind and the magnetic field of the sun.
The solar wind (plasma) slams into the plasma
surrounding the coma. This produces a shock
front (a region of higher density) because the
velocity of the solar wind is reduced. The result
is a pileup of other solar wind particles in the
region. This forces the magnetic field lines
of the sun which are in the vicinity of the coma to also
slow wrap themselves around the coma and sweeping
in back of it to form the
I_______________ tail. This tail is usually
STRAIGHT/CURVED (circle one) and
YELLOW/BLUE (circle one) in color.
17. Meanwhile, the dust escaping from the nucleus is also dragged into
the coma by the jetting
action of the ______________ which are escaping
from the warmed nucleus. The velocities of
the dust particles are modified by the flow
of these gases and may even be coupled to the
magnetic field sweeping around the comet. The
pressure of sunlight also pushes particles one
micron in size or smaller in back of the nucleus
to form the _______________ tail which is
shining through the process of s_______________
(reflected) light. This tail is usually
STRAIGHT/CURVED (circle one) and YELLOW/BLUE
(circle one) in color.
18. When light is _______________, the rays which are passing the
small particles of dust are
deflected (bent) from their straight line paths.
Some of this light reaches us to reveal the location
of the dust tail. This is different from _________________
light which "bounces" off a larger
particle allowing it to be viewed directly.
19. The beautiful blue tail that Hyakutake produced during the latter
part of March 1996 was an
excellent example of an _______________ tail.
Hyakutake was a dust poor comet.
20. With respect to direction, a comet's tail always points TOWARD/AWAY
(circle one) from
the sun. When a comet enters the solar system,
it comes in ________________ first and
_________________ second. However, when a comet
leaves the solar system, it exits
_________________ first and _________________
DISCOVERING A COMET
21. About 5-10 / 10-20 / 20-30 (circle one) new comets are discovered
each year. Because they
are generally faint, diffuse objects when first
seen, WIDE FIELD/NARROW FIELD (circle
one) telescopes and cameras are usually employed
in cometary searches. Because new comets
can be found in any part of the sky, and searching
for them can be a very time-consuming
enterprise, AMATEUR/PROFESSIONAL (circle one)
astronomers play a significant role in
new cometary discoveries. Since most comets
are brightest when near perihelion, they are
generally discovered in the vicinity of the
_______________. Therefore, a good time to go out
and search for comets would be before _______________
or after _______________.
22. Once a comet is discovered it is named after the _______________(s)
who discovered it.
The family names of as many as ONE/TWO/THREE
(circle one) people can be attached to the
object. See the answer section for the new naming
23. Within several days after discovery an _______________ is calculated.
astronomers the ability to describe the path
of the comet within the framework of the solar
system bodies and in what part of the sky it
will be seen from earth.
BRIGHTNESS OF A COMET
24. Once this is completed the brightness or _______________ of the
comet at different
distances from the earth can be calculated.
25. The difference in intensity between one whole magnitude is _______________.
the comet, the more POSITIVE/NEGATIVE (circle
one) the magnitude of the object.
26. Determining the brightness of a comet is a difficult task to accomplish
because the comet
produces light through two processes: _______________
27. The change in brightness of a comet due to its distance from the
_______________ varies as
the inverse square of this distance (1/d²).
This means that if the distance of the comet is halved,
the brightness of the comet will increase _______________
28. The change in brightness of the comet due to its distance from
the _______________ is
another matter. As this distance is halved the
comet's brightness can increase by (1/d²) to
(1/d ^ 6), or from _______________ to _______________
times. This can make a huge
difference as to whether the comet becomes a
spectacular apparition or a dud.
29. Many times comets arriving from the Oort cloud for the first time
may have a layer of easily
sublimed volatiles which cause the comet to
appear abnormally _______________ for its
distance away from the sun. One of the most
overrated comets to fit this scenario was Comet
Kohoutek of 1973-74. During the spring of 1990,
Comet Austin also pulled this same stunt. On the
other hand, Hyakutake blossomed into beautiful object in 1996, and Hale-Bopp
is right on
target to give an equally fine performance in
30. The end result of a comet may be the total disintegration of the
object or the exhaustion of all
volatiles and the misinterpretation of this
body for an _______________.
31. Over tens of thousands of years, the _______________ from the
tails of comets gradually
disperses as a result of the _______________
perturbations of the planets and the slowing of
their orbital velocities due to the *Poynting-Robertson
effect. In the latter situation, dust which
absorbs energy from the sunward direction, radiates
infrared energy back into space more
effectively in the direction opposite to its
orbital motion. This slows the velocity of the dust,
causing the particles to eventually ________________
into the sun.
32. If a dust particle from a comet's tail enters the atmosphere of
the earth, a _______________
is the result.
33. The streak of light which is seen in the sky IS/IS NOT (circle
one) a result of the glow of the
dust particle itself.
34. The very rapid motion (7-45 miles/second or 11-72 km/sec) of the
particle through the
atmosphere causes the cylinder of air through
which the particle is passing to
_______________ revealing the location of the
particle. The actual object disintegrates and/or
is vaporized in the process. Beyond 45 miles
per second (72 km/sec) the object is moving too
fast to be a part of the solar system. Seven
miles per second (11 km/sec) represents the escape
velocity of earth and the lower limit of meteor
35. When a meteor is observed, the event is usually occurring at an
altitude of 5-10 / 10-40 / 40-
70 (circle one) miles above the earth's surface.
36. At certain times of the year an observer may view, over a period
of several hours, numerous
meteors radiating from the same location in
the sky. At these times the earth's orbital plane is
intersecting the orbital plane of a _______________.
These events are called
____________________ (two words).
37. The fact that meteors appear to be diverging from a _______________
indicates that the
particles are traveling ________________ to
each other. As they approach the observer they
_______________, similar to what a person would
expect if she/he were standing on a long,
straight section of railroad tracks which stretched
in front of the viewer to a vanishing point.
38. An extremely bright meteor is usually referred to as a _________________.
39. A dust or rock fragment in orbit about the sun is referred to
as a _________________. If it is
much larger the term _________________ would
40. Objects which enter the atmosphere and strike the earth or other
planets or moons are called
________________. No fireball from a meteor
shower has ever been witnessed to fall to
earth. Therefore it is assumed that meteors
originate from _________________ while the
natural objects that fall to earth to become
meteorites originate in the
_______________________ (two words) between
41. There are three broad classifications of meteorites which are
_________________, _________________, __________________.
42. The most common variety, called _________________, are basically
_________________ material intermixed with varying
amounts of iron in the form of flecks.
Many also have inclusions called ch_______________
composed usually of olivine and
pyroxene, silicate minerals with higher concentrations
of iron and magnesium.
43. _________________ meteorites are composed primarily of iron with
up to 13 percent nickel
mixed throughout. Although this type of meteorite
is not commonly the type recovered from a
witnessed fall, they are the predominate meteorites
associated with finds because they
44. The fact that stony and iron meteorites exist, indicates that
the parent bodies to which these
specimens originally belonged probably had silicate
crusts and iron cores. In other words, these
objects were chemically _______________.
45. The least common variety, called _______________, are composed
of a mixture of silicates
and native iron which probably originated from
the transition zone of a body that was
differentiated, or from a totally undifferentiated
46. All meteorites are about _______________ years of age, indicating
that they are examples of
unchanged original solar system material.
47. Meteorites as a whole are an excellent indicator of the bulk ______________
of the terrestrial bodies of the solar system.
Stony meteorites give geologists insight into the bulk composition of
48. The orbital velocities of small meteorites (several yards in diameter)
striking the earth's surface
are FULLY/NOT FULLY (circle one) slowed to a
free fall by the earth's atmosphere. Giant
meteorites strike the earth at velocities of
FEET PER SECOND/MILES PER SECOND (circle one).
49. When a large meteorite strikes the earth or another astronomical
body a _______________ is formed which is BIGGER
THAN/AS BIG AS (circle one) the impacting body. The kinetic
energy (energy of motion) of the meteorite is
converted into _______________ which
vaporizes the original meteorite and the ground
in the immediate target zone. The impact event
looks very much like a rock being tossed into
50. The floor of the meteorite crater is always _________________
than the surrounding terrain.
The crater walls are always _________________
than the surrounding terrain.
51. The best example of a meteorite crater in the world is found near
Winslow, Arizona and is
called ________________________. The crater
is PROPERLY/IMPROPERLY named
(circle one). Winslow is about three hours southeast
of the south rim of the Grand Canyon if
your are driving. The event which formed this
crater occurred about 25-50,000 years ago.